The first time I experienced a twinge of doubt on the subject was when I learned that carbon dioxide (CO2) comprised less than 0.04 percent of the atmosphere. In truth, such a seemingly small amount shouldn’t be underestimated since CO2 starts trapping heat quite effectively at far more minuscule concentrations. But at the time, I thought, “That’s strange. I would have thought it was a lot more.”

The point is I had been barraged with so much global warming hysteria that I figured CO2 must comprise one percent or five percent or 10 percent of the atmosphere. But since it was only 0.04 percent, it seemed to me that the people making the case for global warming should be more careful and to not exaggerate their claims—to not lose credibility.